[Xen-devel] [PATCH v2 for-4.10] ubsan: add clang 5.0 support

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

clang 5.0 changed the layout of the type_mismatch_data structure and
introduced __ubsan_handle_type_mismatch_v1 and
__ubsan_handle_pointer_overflow.

This commit adds support for the new structure layout, adds the
missing handlers and the new types for type_check_kinds.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
---
ubsan is an optional feature, not enabled by default and not designed
to be used by production systems. Since this change only touches ubsan
code and it's a bugfix in order for clang to work, I argue it should
be merged into 4.10.
---
Changes since v1:
 - Replace message in __ubsan_handle_pointer_overflow.
 - Add a suppress_report check in __ubsan_handle_type_mismatch_v1.
---
 xen/common/ubsan/ubsan.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 xen/common/ubsan/ubsan.h | 11 +++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/xen/common/ubsan/ubsan.c b/xen/common/ubsan/ubsan.c
index fbe568562a..2eaa403691 100644
--- a/xen/common/ubsan/ubsan.c
+++ b/xen/common/ubsan/ubsan.c
@@ -33,7 +33,10 @@ const char *type_check_kinds[] = {
        "member call on",
        "constructor call on",
        "downcast of",
-       "downcast of"
+       "downcast of",
+       "upcast of",
+       "cast to virtual base of",
+       "_Nonnull binding to",
 };
 
 #define REPORTED_BIT 31
@@ -333,6 +336,26 @@ void __ubsan_handle_type_mismatch(struct 
type_mismatch_data *data,
 }
 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
 
+void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
+                               unsigned long ptr)
+{
+       struct type_mismatch_data d = {
+               .location = data->location,
+               .type = data->type,
+               .alignment = 1ul << data->log_alignment,
+               .type_check_kind = data->type_check_kind,
+       };
+
+       /*
+        * NB: do the check with data->location, d->location is just a local
+        * copy and the modifications will be lost.
+        */
+       if (suppress_report(&data->location))
+               return;
+
+       __ubsan_handle_type_mismatch(&d, ptr);
+}
+
 void __ubsan_handle_nonnull_arg(struct nonnull_arg_data *data)
 {
        unsigned long flags;
@@ -478,3 +501,24 @@ void __ubsan_handle_load_invalid_value(struct 
invalid_value_data *data,
        ubsan_epilogue(&flags);
 }
 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
+
+void __ubsan_handle_pointer_overflow(struct pointer_overflow_data *data,
+                               unsigned long base, unsigned long result)
+{
+       unsigned long flags;
+
+       if (suppress_report(&data->location))
+               return;
+
+       ubsan_prologue(&data->location, &flags);
+
+       if (((long)base >= 0) == ((long)result >= 0))
+               pr_err("pointer operation %s %p to %p\n",
+                       base > result ? "underflowed" : "overflowed",
+                       (void *)base, (void *)result);
+       else
+               pr_err("pointer index expression with base %p overflowed to 
%p\n",
+                       (void *)base, (void *)result);
+
+       ubsan_epilogue(&flags);
+}
diff --git a/xen/common/ubsan/ubsan.h b/xen/common/ubsan/ubsan.h
index b2d18d4a53..2710cd423e 100644
--- a/xen/common/ubsan/ubsan.h
+++ b/xen/common/ubsan/ubsan.h
@@ -36,6 +36,13 @@ struct type_mismatch_data {
        unsigned char type_check_kind;
 };
 
+struct type_mismatch_data_v1 {
+       struct source_location location;
+       struct type_descriptor *type;
+       unsigned char log_alignment;
+       unsigned char type_check_kind;
+};
+
 struct nonnull_arg_data {
        struct source_location location;
        struct source_location attr_location;
@@ -73,6 +80,10 @@ struct invalid_value_data {
        struct type_descriptor *type;
 };
 
+struct pointer_overflow_data {
+       struct source_location location;
+};
+
 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
 typedef __int128 s_max;
 typedef unsigned __int128 u_max;
-- 
2.13.5 (Apple Git-94)


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